.\"	$NetBSD: unlink.2,v 1.28 2013/07/28 13:53:04 njoly Exp $
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.\"     @(#)unlink.2	8.1 (Berkeley) 6/4/93
.\"
.Dd July 28, 2013
.Dt UNLINK 2
.Os
.Sh NAME
.Nm unlink ,
.Nm unlinkat ,
.Nd remove directory entry
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn unlink "const char *path"
.In fcntl.h
.Ft int
.Fn unlinkat "int fd" "const char *path" "int flag"
.Sh DESCRIPTION
The
.Fn unlink
function
removes the link named by
.Fa path
from its directory and decrements the link count of the
file which was referenced by the link.
If that decrement reduces the link count of the file
to zero,
and no process has the file open, then
all resources associated with the file are reclaimed.
If one or more process have the file open when the last link is removed,
the link is removed, but the removal of the file is delayed until
all references to it have been closed.
.Pp
.Fn unlinkat
works the same way as
.Fn unlink
except if
.Fa path
is relative.
In that case, it is looked up from a directory whose file
descriptor was passed as
.Fa fd .
Search permission is required on this directory.
.\"    (These alternatives await a decision about the semantics of O_SEARCH)
.\" Search permission is required on this directory
.\" except if
.\" .Fa fd
.\" was opened with the
.\" .Dv O_SEARCH
.\" flag.
.\"    - or -
.\" This file descriptor must have been opened with the
.\" .Dv O_SEARCH
.\" flag.
.Fa fd
can be set to
.Dv AT_FDCWD
in order to specify the current directory.
.Pp
.Fn unlinkat
will remove directories just like
.Fn rmdir
provided
.Dv AT_REMOVEDIR
is set in
.Fa flag .
.Sh RETURN VALUES
.Rv -std unlink unlinkat
.Sh ERRORS
The
.Fn unlink
and
.Fn unlinkat
succeeds unless:
.Bl -tag -width Er
.It Bq Er EACCES
Search permission is denied for a component of the path prefix, or
write permission is denied on the directory containing the link
to be removed.
.It Bq Er EBUSY
The entry to be unlinked is the mount point for a
mounted file system.
.It Bq Er EFAULT
.Fa path
points outside the process's allocated address space.
.It Bq Er EIO
An I/O error occurred while deleting the directory entry
or deallocating the inode.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded
.Brq Dv NAME_MAX
characters, or an entire path name exceeded
.Brq Dv PATH_MAX
characters.
.It Bq Er ENOENT
The named file does not exist.
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er EPERM
The named file is a directory and the effective user ID
of the process is not the super-user, the file system
containing the file does not permit the use of
.Fn unlink
on a directory,
or the directory containing the file is marked sticky,
and neither the containing directory nor the file to be removed
are owned by the effective user ID.
.It Bq Er EROFS
The named file resides on a read-only file system.
.El
.Pp
In addition,
.Fn unlinkat
will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
.Fa path
does not specify an absolute path and
.Fa fd
is neither
.Dv AT_FDCWD
nor a valid file descriptor open for reading or searching.
.It Bq Er ENOTDIR
.Fa path
is not an absolute path and
.Fa fd
is a file descriptor associated with a non-directory file; or
.Fa flag
has
.Dv AT_REMOVEDIR
set and
.Fa path
does not name a directory.
.It Bq Er ENOTEMPTY
.Fa flag
has
.Dv AT_REMOVEDIR
set and
.Fa path
is a directory that is not empty.
.El
.Sh SEE ALSO
.Xr close 2 ,
.Xr link 2 ,
.Xr rmdir 2 ,
.Xr symlink 7
.Sh STANDARDS
The
.Fn unlink
function conforms to
.St -p1003.1-90 .
.Fn unlinkat
conforms to
.St -p1003.1-2008 .
.Sh HISTORY
An
.Fn unlink
function call appeared in
.At v2 .
